Design of New Polyaspartamide Copolymers for siRNA Delivery in Antiasthmatic Therapy

Enzymatically Cross-Linked Hydrogel Beads Based on a Novel Poly(aspartamide) Derivative

In recent years, hydrogel beads and in situ hydrogels have gained wide attention in various fields such as biomedicine. In this study, 3-(4-hydroxyphenyl) propionic acid (HP) was introduced into the side chain of poly(α,β-[N-(2-hydroxyethyl)-D,L-aspartamide]) (PHEA) to synthesize phenolic hydroxyl-functionalized poly(aspartamide) derivative PHEA-HP with enzyme-catalyzed cross-linking potential. First, the chemical structure of PHEA-HP was characterized by FT-IR, UV and 1H NMR, and the results of in vitro cytotoxicity against L929 cell line and hemolysis experiment showed that PHEA-HP did not have toxicity to cells (viability > 90%) and had good blood compatibility. Then, rheological measurement confirmed the formation of PHEA-HP-based in situ hydrogel with a high storage modulus (G') around 104 Pa, and the vial-tilting method revealed that the gelation time of PHEA-HP aqueous solution could be tuned in the wide range of 5-260 s by varying the concentrations of hydrogen peroxide (H2O2) and horseradish peroxidase (HRP). Finally, hydrogel beads of different diameters containing methylene blue (for easy observation) were prepared using a coaxial needle and syringe pumps, and the effect of the flow rate of the outer phase on the diameters of the hydrogel beads was also investigated. Therefore, PHEA-HP may be a promising and safe poly(aspartamide) derivative that can be used to prepare in situ hydrogels and hydrogel beads for applications closely related to the human body.

Diving into RNAi Therapy: An Inhalable Formulation Based on Lipid-Polymer Hybrid Systems for Pulmonary Delivery of siRNA

Here, a pulmonary formulation based on lipid-polymer hybrid nanoparticles carrying small interfering RNA (siRNA) was developed to realize a RNA interference-based therapy to treat respiratory diseases. Toward this aim, a new copolymer was synthesized, by functionalization of the α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide with 35 mol % of 1,2-bis(3-aminopropylamino)ethane, 0.4 mol % of fluorescent dye, and 4.5 mol % of poly(lactic-co-glycolic acid). This was used to encapsulate siRNA targeting the green fluorescent protein (siGFP), within a lipid shell made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-distearoyl-sn-glycero-phosphoethanolamine-N-(polyethylene glycol)2000. siGFP-loaded lipid-polymer hybrid nanoparticles (LPHFNPs@siGFP) exhibited colloidal size (∼164 nm), positive ζ potential, high siRNA encapsulation efficiency (∼99%), and a core-shell morphology. They showed high cellular uptake and a gene silencing efficiency of ∼50% in human lung cancer cells expressing GFP. To address aerodynamic challenges, LPHFNPs@siGFP were spray-dried with trehalose, yielding spherical particles (∼3 μm) with 80% siRNA encapsulation efficiency, excellent aerosolization properties, and a gene silencing efficiency comparable to the fresh LPHFNPs@siGFP sample.

Design of Experiments Grants Mechanistic Insights into the Synthesis of Spermine-Containing PBAE Copolymers

Successful therapeutic delivery of siRNA with polymeric nanoparticles seems to be a promising but not vastly understood and complicated goal to achieve. Despite years of research, no polymer-based delivery system has been approved for clinical use. Polymers, as a delivery system, exhibit considerable complexity and variability, making their consistent production a challenging endeavor. However, a better understanding of the polymerization process of polymer excipients may improve the reproducibility and material quality for more efficient use in drug products. Here, we present a combination of Design of Experiment and Python-scripted data science to establish a prediction model, from which important parameters can be extracted that influence the synthesis results of polybeta-amino esters (PBAEs), a common type of polymer used preclinically for nucleic acid delivery. We synthesized a library of 27 polymers, each one at different temperatures with different reaction times and educt ratios using an orthogonal central composite (CCO-) design. This design allowed a detailed characterization of factor importance and interactions using a very limited number of experiments. We characterized the polymers by analyzing the resulting composition by 1H-NMR and the size distribution by GPC measurements. To further understand the complex mechanism of block polymerization in a one-pot synthesis, we developed a Python script that helps us to understand possible step-growth steps. We successfully developed and validated a predictive response surface and gathered a deeper understanding of the synthesis of polyspermine-based amphiphilic PBAEs.

TAT decorated siRNA polyplexes for inhalation delivery in anti-asthma therapy

In this work, a novel protonable copolymer was designed to deliver siRNA through the inhalation route, as an innovative formulation for the management of asthma. This polycation was synthesized by derivatization of α,β-poly(N-2-hydroxyethyl)D,L-aspartamide (PHEA) first with 1,2-Bis(3-aminopropylamino)ethane (bAPAE) and then with a proper amount of maleimide terminated poly(ethylene glycol) (PEG-MLB), with the aim to increase the superficial hydrophilicity of the system, allowing the diffusion trough the mucus layer. Once the complexation ability of the copolymer has been evaluated, obtaining nanosized polyplexes, polyplexes were functionalized on the surface with a thiolated TAT peptide, a cell-penetrating peptide (CPP), exploiting a thiol-ene reaction. TAT decorated polyplexes result to be highly cytocompatible and able to retain the siRNA with a suitable complexation weight ratio during the diffusion process through the mucus. Despite polyplexes establish weak bonds with the mucin chains, these can diffuse efficiently through the mucin layer and therefore potentially able to reach the bronchial epithelium. Furthermore, through cellular uptake studies, it was possible to observe how the obtained polyplexes penetrate effectively in the cytoplasm of bronchial epithelial cells, where they can reduce IL-8 gene expression, after LPS exposure. In the end, in order to obtain a formulation administrable as an inhalable dry powder, polyplexes were encapsulated in mannitol-based microparticles, by spray freeze drying, obtaining highly porous particles with proper technological characteristics that make them potentially administrable by inhalation route.

Airway mucus in pulmonary diseases: Muco-adhesive and muco-penetrating particles to overcome the airway mucus barriers

Airway mucus is a complex viscoelastic gel that provides a defensive physical barrier and shields the airway epithelium by trapping inhaled foreign pathogens and facilitating their removal via mucociliary clearance (MCC). In patients with respiratory diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), non-CF bronchiectasis, and asthma, an increase in crosslinking and physical entanglement of mucin polymers as well as mucus dehydration often alters and typically reduces mucus mesh network pore size, which reduces neutrophil migration, decreases pathogen capture, sustains bacterial infection, and accelerates lung function decline. Conventional aerosol particles containing hydrophobic drugs are rapidly captured and removed by MCC. Therefore, it is critical to design aerosol delivery systems with the appropriate size and surface chemistry that can improve drug retention and absorption with the goal of increased efficacy. Biodegradable muco-adhesive particles (MAPs) and muco-penetrating particles (MPPs) have been engineered to achieve effective pulmonary delivery and extend drug residence time in the lungs. MAPs can be used to target mucus as they get trapped in airway mucus by steric obstruction and/or adhesion. MPPs avoid muco-adhesion and are designed to have a particle size smaller than the mucus network, enhancing lung retention of particles as well as transport to the respiratory epithelial layer and drug absorption. In this review, we aim to provide insight into the composition of airway mucus, rheological characteristics of airway mucus in healthy and diseased subjects, the most recent techniques to study the flow dynamics and particle diffusion in airway mucus (in particular, multiple particle tracking, MPT), and the advancements in engineering MPPs that have contributed to improved airway mucus penetration, lung distribution, and retention.

Galactosylated Polymer/Gold Nanorods Nanocomposites for Sustained and Pulsed Chemo-Photothermal Treatments of Hepatocarcinoma

In this paper, we propose a rational design of a hybrid nanosystem capable of locally delivering a high amount of hydrophobic anticancer drugs (sorafenib or lenvatinib) and heat (hyperthermia) in a remote-controlled manner. We combined in a unique nanosystem the excellent NIR photothermal conversion of gold nanorods (AuNRs) with the ability of a specially designed galactosylated amphiphilic graft copolymer (PHEA-g-BIB-pButMA-g-PEG-GAL) able to recognize hepatic cells overexpressing the asialoglycoprotein receptor (ASGPR) on their membranes, thus giving rise to a smart composite nanosystem for the NIR-triggered chemo-phototherapy of hepatocarcinoma. In order to allow the internalization of AuNRs in the hydrophobic core of polymeric nanoparticles, AuNRs were coated with a thiolated fatty acid (12-mercaptododecanoic acid). The drug-loaded hybrid nanoparticles were prepared by the nanoprecipitation method, obtaining nanoparticles of about 200 nm and drug loadings of 9.0 and 5.4% w/w for sorafenib and lenvatinib, respectively. These multifunctional nanosystems have shown to convert NIR radiation into heat and release charged drugs in a remote-controlled manner. Then, the biocompatibility and synergistic effects of a chemo-phototherapy combination, as well the receptor-mediated internalization, were evaluated by an in vitro test on HepG2, HuH7, and NHDF. The results indicate that the proposed nanoparticles can be considered to be virtuous candidates for an efficient and selective dual-mode therapy of hepatocarcinoma.

Nanocarriers for delivery of siRNA as gene silencing mediator

The term nanocarrier refers to sub-micrometric particles of less than 100 nm, designed to transport, distribute, and release nanotechnology-based drug delivery systems. siRNA therapy is a novel strategy that has great utility for a variety of treatments, however naked siRNA delivery has not been an effective strategy, resulting in the necessary use of nanocarriers for delivery. This review aims to highlight the versatility of carriers based on smart drug delivery systems. The nanocarriers based on nanoparticles as siRNA DDS have provided a set of very attractive advantages related to improved physicochemical properties, such as high surface-to-volume ratio, versatility to package siRNA, provide a dual function to both protect extracellular barriers that lead to elimination and overcome intracellular barriers limiting cytosolic delivery, and possible chemical modifications on the nanoparticle surface to improve stability and targeting. Lipid and polymeric nanocarriers have proven to be stable, biocompatible, and effective in vitro, further exploration of the development of new nanocarriers is needed to obtain safe and biocompatible tools for effective therapy.

Correlating Rheological Properties of a Gellan Gum-Based Bioink: A Study of the Impact of Cell Density

Here, for the production of a bioink-based gellan gum, an amino derivative of this polysaccharide was mixed with a mono-functionalized aldehyde polyethyleneglycol in order to improve viscoelastic macroscopic properties and the potential processability by means of bioprinting techniques as confirmed by the printing tests. The dynamic Schiff base linkage between amino and aldehyde groups temporally modulates the rheological properties and allows a reduction of the applied pressure during extrusion followed by the recovery of gellan gum strength. Rheological properties, often related to printing resolution, were extensively investigated confirming pseudoplastic behavior and thermotropic and ionotropic responses. The success of bioprinting is related to different parameters. Among them, cell density must be carefully selected, and in order to quantify their role on printability, murine preostoblastic cells (MC3T3-E1) and human colon tumor cells (HCT-116) were chosen as cell line models. Here, we investigated the effect of their density on the bioink’s rheological properties, showing a more significant difference between cell densities for MC3T3-E1 compared to HCT-116. The results suggest the necessity of not neglecting this aspect and carrying out preliminary studies to choose the best cell densities to have the maximum viability and consequently to set the printing parameters.

Long Noncoding RNA Hotair Promotes the Progression and Immune Escape in Laryngeal Squamous Cell Carcinoma through MicroRNA-30a/GRP78/PD-L1 Axis

Homeobox (HOX) transcript antisense RNA (Hotair) is elevated in many cancers significantly. However, the oncogenic role of Hotair in human laryngeal squamous cell carcinoma (LSCC) is still unknown. Thus, we explored the expression profile of Hotair and its function in LSCC. We observed high expression levels of Hotair in six LSCC cell lines compared to the human nasopharyngeal epithelial cell line. Knockdown of Hotair inhibited proliferation and enhanced apoptosis of Tu212 and Hep-2 cell lines in vitro. Moreover, the overexpression of hsa-miR-30a-5p inhibited the expression of GRP78 and PD-L1, but Hotair overexpression in LSCC cells rescues both proteins. Furthermore, the impacts of hsa-miR-30a-5p upregulation on the apoptosis and proliferation of LSCC cells were rescued by overexpression of Hotair. Finally, we combined si-Hotair and a VEGF inhibitor to treat LSCC cells in vitro or in vivo and surprisingly observed a significant inhibition of LSCC growth. In summary, these results indicate that Hotair displays an oncogenic role in both malignancy and immune escape in LSCC related to hsa-miR-30a-5p/GRP78/PD-L1 signaling. Therefore, Hotair may be a potential target for treating LSCC.

Stimuli-Responsive Poly(aspartamide) Derivatives and Their Applications as Drug Carriers

Poly(aspartamide) derivatives, one kind of amino acid-based polymers with excellent biocompatibility and biodegradability, meet the key requirements for application in various areas of biomedicine. Poly(aspartamide) derivatives with stimuli-responsiveness can usually respond to external stimuli to change their chemical or physical properties. Using external stimuli such as temperature and pH as switches, these smart poly(aspartamide) derivatives can be used for convenient drug loading and controlled release. Here, we review the synthesis strategies for preparing these stimuli-responsive poly(aspartamide) derivatives and the latest developments in their applications as drug carriers.

Development of polymer-based nanoparticles for zileuton delivery to the lung: PMeOx and PMeOzi surface chemistry reduces interactions with mucins

In this paper, two amphiphilic graft copolymers were synthesized by grafting polylactic acid (PLA) as hydrophobic chain and poly(2-methyl-2-oxazoline) (PMeOx) or poly(2-methyl-2-oxazine) (PMeOzi) as hydrophilic chain, respectively, to a backbone of α,β-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA). These original graft copolymers were used to prepare nanoparticles delivering Zileuton in inhalation therapy. Among various tested methods, direct nanoprecipitation proved to be the best technique to prepare nanoparticles with the smallest dimensions, the narrowest dimensional distribution and a spherical shape. To overcome the size limitations for administration by inhalation, the nano-into-micro strategy was applied, encapsulating the nanoparticles in water-soluble mannitol-based microparticles by spray-drying. This process has allowed to produce spherical microparticles with the proper size for optimal lung deposition, and, once in contact with fluids mimicking the lung district, able to dissolve and release non-aggregated nanoparticles, potentially able to spread through the mucus, releasing about 70% of the drug payload in 24 h.

Development of New Targeted Inulin Complex Nanoaggregates for siRNA Delivery in Antitumor Therapy

Here, a novel strategy of formulating efficient polymeric carriers based on the already described INU-IMI-DETA for gene material whose structural, functional, and biological properties can be modulated and improved was successfully investigated. In particular, two novel derivatives of INU-IMI-DETA graft copolymer were synthesized by chemical functionalisation with epidermal growth factor (EGF) or polyethylenglycol (PEG), named INU-IMI-DETA-EGF and INU-IMI-DETA-PEG, respectively, in order to improve the performance of already described "inulin complex nanoaggregates" (ICONs). The latter were thus prepared by appropriately mixing the two copolymers, by varying each component from 0 to 100 wt% on the total mixture, named EP-ICONs. It was seen that the ability of the INU-IMI-DETA-EGF/INU-IMI-DETA-PEG polymeric mixture to complex siGL3 increases with the increase in the EGF-based component in the EP-ICONs and, for each sample, with the increase in the copolymer:siRNA weight ratio (R). On the other hand, the susceptibility of loaded siRNA towards RNase decreases with the increase in the pegylated component in the polymeric mixture. At all R values, the average size and the zeta potential values are suitable for escaping from the RES system and suitable for prolonged intravenous circulation. By means of biological characterisation, it was shown that MCF-7 cells are able to internalize mainly the siRNA-loaded into EGF-decorated complexes, with a significant difference from ICONs, confirming its targeting function. The targeting effect of EGF on EP-ICONs was further demonstrated by a competitive cell uptake study, i.e., after cell pre-treatment with EGF. Finally, it was shown that the complexes containing both EGF and PEG are capable of promoting the internalisation and therefore the transfection of siSUR, a siRNA acting against surviving mRNA, and to increase the sensitivity to an anticancer agent, such as doxorubicin.